Biology subjects

May, P. J. C.

Publications and source records attributed to May, P. J. C..

2 recordsLinked to original sources

bioRxiv2024

Brain Segregation and Integration Relate to Word-Finding Abilities in Older and Younger Adults

Previous research has shown that word-finding difficulties in older age are associated with functional and structural brain changes. However, the use of functional brain networks, measured through electroencephalography, to predict word-finding in older and younger adults has not yet been investigated. This study utilised resting-state electroencephalography data (61 channels) from the Leipzig Study for Mind-Body-Emotion Interactions dataset (Babayan et al., 2019) to investigate the relationship between functional brain networks and word-finding ability in healthy younger and older adults. Graph theory-based measures in individualised delta, theta, alpha, and beta bands were computed to assess brain segregation and integration of 53 older (aged 59-77) and 53 younger right-handed adults (aged 20-35). Word-finding ability was quantified as the number of orally produced words during a semantic and letter fluency task. Multiple linear regression revealed that, in older adults, greater functional connectedness in the delta band was associated with lower semantic fluency. Irrespective of age, greater modularity in the alpha band was related to lower semantic fluency. A greater small-world index in the delta band was related to better semantic fluency, irrespective of age. Increased brain integration in the delta band corresponded to greater semantic fluency in older adults. Hence, word-finding ability seems to be related to brain segregation and integration specific to the frequency band, possibly indicating alterations in cognitive control or compensatory shifts to less functionally specific frequency bands. The article further provides a discussion on neural dedifferentiation, hyper-synchronisation, study limitations, and directions for future research.

neuroscience↗

bioRxiv2024

Hemispheric difference of adaptation lifetime in human auditory cortex measured with MEG

Adaptation is the attenuation of a neuronal response when a stimulus is repeatedly presented. The phenomenon has been linked to sensory memory, but its exact neuronal mechanisms are under debate. One defining feature of adaptation is its lifetime, that is, the timespan over which the attenuating effect of previous stimulation persists. This can be revealed by varying the stimulus-onset interval (SOI) of the repeated stimulus. As SOI is increased, the peak amplitude of the response grows before saturating at large SOIs. The rate of this growth can be quantified and used as an estimate of adaptation lifetime. Here, we studied whether adaptation lifetime varies across the left and the right auditory cortex of the human brain. Event-related fields of whole-head magnetoencephalograms (MEG) were measured in 14 subjects during binaural presentation of pure tone stimuli. To make statistical inferences on the single-subject level, additional event-related fields were generated by resampling the original single-trial data via bootstrapping. For each hemisphere and SOI, the peak amplitude of the N1m response was then derived from both original and bootstrap-based data sets. Finally, the N1m peak amplitudes we used for deriving subject-and hemisphere-specific estimates of adaptation lifetime. Comparing subject-specific adaptation lifetime across hemispheres, we found a significant difference, with longer adaptation lifetimes in the left than in the right auditory cortex (p = 0.004). This difference might have a functional relevance in the context of temporal binding of auditory stimuli, leading to larger integration time windows in the left than in the right hemisphere.

neuroscience↗